General buckling pressure, tension ring area, bolt/fastener allowable stress, panel and seismic loads, and physical/appurtenance limits for structurally-supported aluminum dome roofs
◉ API 650 11TH ED. WITH ADDENDA THROUGH ADDENDUM 3, APPENDIX G · NOT A REGULATORY SUBMISSION TOOL
⚠ Indicative tool only. Source: API 650 Appendix G, read directly from the same 11th-edition (through Addendum 3) text used elsewhere in Tank Protocol — not from any vendor specification or older edition. Appendix G is an alternative code path to ANSI/AWWA D108 for aluminum dome roofs (see the separate AWWA D108 tool); a Purchaser selects one or the other, not both, and the two have materially different criteria — for example AWWA D108 permits a dome radius up to 1.4×D, while this appendix caps it at 1.2×D. When this appendix applies, it supersedes §5.10 and the roof-design parts of Appendix F (§G.1.1); all other API 650 requirements still apply, and the maximum design temperature is capped at 90°C (200°F) under this appendix specifically.
Two vendor documents reviewed alongside this appendix (Tank Connection's APEX Domes specifications) restate G's requirements accurately but add their own default assumptions not found in the code itself — e.g. a 90 mph default wind speed (API 650's own data sheet, Figure G-1, instead offers 120 mph, a Purchaser-specified value, or an ASCE 7 gust speed) and a 2.34 minimum fastener safety factor on ultimate strength. Those are that manufacturer's typical practice, not an API 650 requirement, and are not included in this tool.
Identification
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1. General Buckling Pressure (§G.4.1.3, Eq. G.4.1.3-1)
SF = 1.65 fixed by the appendix. Alternatively, p\u2090 may be determined by non-linear finite element analysis at the same safety factor \u2014 this tool only performs the closed-form check.
2. Net Tension Ring Area (§G.4.1.4, Eq. G.4.1.4-1)
This formula excludes bending stresses from panel loads on the beam \u2014 those must be considered separately in the tension ring design per §G.3.1 (Aluminum Design Manual).
3. Design Loads (§G.4.2, §G.4.3)
Panel loads (§G.4.2.3): 3 kPa (60 lbf/ft²) uniform over the full panel, or two 1100 N (250 lbf) concentrated loads each over separate 0.1 m² (1 ft²) areas — not applied simultaneously with each other or with any other load. Internal pressure (§G.4.3): unless otherwise specified, not to exceed the roof's own weight, and never more than 2.2 kPa (9 in. water column).